Flip-chip hybridization is a technique where two microelectronic components, for example, an array of photosensitive elements and a circuit for reading it, are independently formed, and where these components are placed on each other while electric interconnects, necessary to their operation, are formed therebetween.
According to the state of the art, the interconnects are made in the form of solder bumps, arranged between metal areas wettable by the material forming the bumps, formed on opposite surfaces of the components. The hybridization method then comprises forming said areas on the surfaces of the components to be hybridized, depositing a solder material on the areas of a first component, placing the second component on the first component while aligning the areas of the two components, and then heating the assembly to a temperature melting the solder material to form the electric interconnects.
This type of hybridization however has the disadvantage of submitting the components to a significant thermal shock, the melting temperature of the materials of the bumps being usually greater than 152° C., this temperature being the melting temperature of the solder material, that is, tin. Such a heating may thus embrittle the components and/or forbid the use of materials which cannot withstand such temperatures, such as plastic materials, particularly PEN (polyethylene naphthalate) and PET (polyethylene terephthalate), which have a vitreous transition temperature usually much lower than the melting temperature of the solder materials.